<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>表单</title>
    <link href="css/bootstrap.min.css" rel="stylesheet"/>
    <script src="js/jquery-3.3.1.min.js"></script>
    <script src="js/bootstrap.min.js"></script>
    <style>
        body{
            margin: 5px;
        }
    </style>
</head>
<body>
<button class="btn btn-primary">蓝色的按钮</button>
<button class="btn btn-success">绿色的按钮</button>
<button class="btn btn-danger">红色的按钮</button>
<button class="btn btn-info">天蓝的的按钮</button>
<button class="btn btn-warning">红色的按钮</button>
<button class="btn btn-default">默认的按钮</button>
</body>
</html>